There are so many template engines for node.js and express and there is even this detailed comparison: http://paularmstrong.github.com/node-templates/index.html This led me to check out EJS, Mu2 and JQTpl and I spent some hours on experimenting which of them fits my needs best.
I know that there already are several questions concerning which framework is best, but none of them concentrates on the possibility of using helpers. I tried to build a form helper (which should render input tags and their values if I pass an object into it) together with all of them but I did not find a straight forward way accomplishing it.
Are there any recommendable modules that enable me to use helpers? Maybe even using mustache.js (which - for me - feels like the best of the ones I tried)? Thanks in advance!
I can't point you to the comparison you are looking for, but nearly all the templating engines I've looked at have had a facility for helpers.
If you are using Express (which you mentioned in your question), you can tell Express what helpers you want to expose to whatever template engine you are using (set via the "view engine" app variable) - see the following sections of the Express Guide for details:
Some template engines come with support for Express built in, although they may require an extra configuration step. I am partial to CoffeeKup (and the more updated fork coffeecup), which lets you write your views in Coffeescript; enabling auto-compilation requires and extra call to the Express server object (and covered in the docs):
app.register('.coffee', coffeecup.adapters.express);
Others may offer an additional node package, you may find npm search express- instructive. For example, express-handlebars specifically fixes up app.helpers() and app.dynamicHelpers() to work with handlebars. (Disclaimer: I haven't used this module personally).